independent review of IBM Flash System 810 (with IBM SVC)

1. IBM FlashSystem 810 and IBM SVC
Previously, products TMS Ramsan not officially supplied to Ukraine. Once this division was sold to IBM - and
the situation has changed for me, on occasion, got TMS Ramsan 810 already in the form of IBM FlashSystem 810.
What came out of it - you can read below.
Configuration tested IBM FlashSystem 810:
- 13x FlashCard eMLC 480GB usable capacity each, 12 - for data, 1 - active spare ( the test configuration is
different from the maximum)
- Host interfaces 4x8Gb FC
- Full set of licenses
it looks all like this

2. -
In SPC-1 at the time of writing, there are no results IBM FlashSystem 810. A similar result is official (but fully
fault-tolerant) IBM FlashSystem 820 в SPC-1– ~195K iops with Average Response Time 1,29ms.
Carry out tests to determine the achievable performance indicators for IBM FlashSystem 810 in this configuration.
And repeat them for situations where IBM FlashSystem 810 virtualized by IBM SVC, to determine - not whether SVC
in such a situation the bottleneck?
In a test environment part of IBM FlashSystem 810 was given directly (over FC-SAN) to the host, and the other part
was presented to the host through a separate pool SVC (single io-group/two node CG8). The host was a dLPAR on
IBM Power Systems 9117 -MMB with AIX 6.1 TL08 SP3 (in this release include native support for IBM FlashSystem
810 and it does not require extra ODM). From SVC and FlashSystem 810 was presented by host 16xLU,
gathered at the stripe by AIX LVM. To organize the data file system was used JFS2 with inline log and mount
options noatime, cio. Each of the filesystems (size to 2TB) was filled with data at > 80%. On IBM SVC all
16xLU were thin (IBM FlashSystem 810 has no similar technology).
.

3. The first test is carried out for a multi-threaded load types - 100% Random, Read/Write = 80/20, by varying
the size of the block (diagram 1, 2). IBM FlashSystem 810 connected to the host via SAN (without IBM SVC).
• block 64KB/128KB reached the maximum bandwidth limited 4x8Gbit FC interfaces.
• relatively low performance with a block size 512B and 2KB, due to the size of the default block used in the file
system JFS2 (4KB)
diagram 1 - IBM FlashSystem 810
100% Random, Read/Write= 80/20
250000
200000
IOPS
150000
100000
50000
0
FlashSystem 810
512B
2KB
4KB
8KB
16KB
32KB
64KB
128KB
54303
54347
225278
191741
167754
89818
51661
25010
diagram 2 - IBM FlashSystem 810
average latency
25
ms
20
15
10
5
0
512B
2KB
4KB
8KB
16KB
32KB
64KB
128KB
FlashSystem 810, write
512B
0.1
2KB
0.1
4KB
0.1
8KB
0.1
16KB
0.1
32KB
0.2
64KB
0.3
128KB
0.4
FlashSystem 810, read
0.2
0.2
0.3
0.5
0.8
1.5
3.5
8.2

4. Repeat the test for multi-threaded load types - 100% Random, Read/Write = 80/20, varying the size of the
block, but presenting IBM FlashSystem 810 to the host through the IBM SVC (diagram 3, 4). As seen in the chart number of digits less than in the previous test. The reason was more than obvious - during the test was recorded
maximum CPU utilization on both nodes SVC. Simultaneously with the reduction of number of iops increased
response time.
diagram 3 - IBM FlashSystem 810 over IBM SVC
100% Random, Read/Write= 80/20
250000
200000
IOPS
150000
100000
50000
0
SVC+FlashSystem 810
512B
2KB
4KB
8KB
16KB
32KB
64KB
128KB
44444
44423
153889
135541
111212
68236
36558
18193
diagram 4 - IBM FlashSystem 810 over IBM SVC
average latency
25
ms
20
15
10
5
0
512B
2KB
4KB
8KB
16KB
32KB
64KB
128KB
SVC+FlashSystem 810, write
512B
0.1
2KB
0.1
4KB
0.5
8KB
0.5
16KB
0.5
32KB
0.4
64KB
0.5
128KB
0.6
SVC+FlashSystem 810, read
0.3
0.3
1.1
1.2
1.8
4
10
20

5. Repeat the test. Leaving unchanged the workload - 100% Random, Read/Write = 80/20. But now turn off
caching on the SVC for the test volumes (Cache Mode Disabled
).
As seen in the chart below (diagram 5, 6) - it has improved a bit in the result iops, but worsened the response time
on large blocks. Again, the limiting factor was the CPU load on SVC nodes.
diagram 5 - IBM FlashSystem 810 over IBM SVC
100% Random, Read/Write= 80/20
250000
200000
iops
150000
100000
50000
0
SVC (Cache disabled)+FlashSystem 810
512B
2KB
4KB
8KB
16KB
32KB
64KB
128KB
45552
46684
191483
169890
133663
79913
40926
18821
diagram 6 - IBM FlashSystem 810 over IBM SVC
average latency
25
ms
20
15
10
5
0
512B
2KB
4KB
8KB
16KB
32KB
64KB
128KB
512B
2KB
4KB
8KB
16KB
32KB
64KB
128KB
SVC (Cache disabled)+FlashSystem 810,
write
0.1
0.1
0.2
0.2
0.2
0.5
1.2
2.2
SVC (Cache disabled)+FlashSystem 810,
read
0.3
0.3
0.6
1
1.5
3.1
9
25

6. Compare previous data (diagram 7, 8).
diagram 7 - iops
250000
200000
150000
100000
50000
0
512B
2KB
4KB
SVC+FlashSystem 810
8KB
16KB
32KB
64KB
SVC (Cache disabled)+FlashSystem 810
128KB
FlashSystem 810
diagram 8 - average R/W latency, ms
25
20
15
10
5
0
512B
2KB
4KB
8KB
16KB
32KB
64KB
128KB
FlashSystem 810, write
SVC (Cache disabled)+FlashSystem 810, write
SVC+FlashSystem 810, write
FlashSystem 810, read
SVC (Cache disabled)+FlashSystem 810, read
SVC+FlashSystem 810, read

7. Dependence in the previous tests on the CPU load of the SVC iops reflected below diagram 9.
diagram 9 - 100% Random, Read/Write= 80/20, block size=8KB
SVC (Cache disabled)+FlashSystem 810
200
150
100
50
19
37
48
59
75
76
80
80
80
80
80
SVC CPU load %
K IOPS
0
8
10
12
14
16
18
20
22
the number of concurrent streams ->
24
26
28

8. Results:
As demonstrated above, the performance of a single IBM FlashSystem 810 is not even in full configuration
outperforms single cluster IBM SVC. (IBM SVC + IBM FlashSystem, still faster than, for example, IBM Storwize V7000
with SSD).
IBM SVC is available for a number of upgrades, in particular - the addition of a second CPU and another 4port FC HBA. In some IBM RedBooks, using IBM SVC and IBM FlashSystem together, have a recommendation upgrade IBM SVC nodes by setting the second FC HBA. But there is no recommendation to add a second processor.
Why? After the above has been demonstrated that for this configuration is the bottleneck is CPU on SVC nodes. The
reason is quite simple - the current code/firmware SVC can use extra CPU only (and exclusively) for Real-time
Compression, because for general computing is not supported by more 4xCPU Core.
Questions?
Oleg Korol
it-expert@ukr.net
http://ua.linkedin.com/pub/oleg-korol/26/920/716